A recent study by C·I·B and University of Liverpool student Tom Bishop and supervisors Mark Robsertson,
Berndt Janse van Rensburg and Catherine Parr has asked how the composition of ant groupings changes across environmental gradients. The
paper made use of data from a long-term ant monitoring programme, initially funded by the C·I·B, from the Sani Pass in the
Maloti-Drakensberg Mountains.

Tom used a number of new methods to assess how the ant communities changed in response to elevation. Firstly, changes
in both the taxonomic and functional structure of the ant communities were analysed. The taxonomic part of the analysis looked at how
species identities changed along the gradient. The functional aspect used morphological data to describe the ecology of the 92 different
ant species. This functional description of the ant fauna recognises that some species are similar to each other than others. For
example, specialist predatory species are more ecologically similar to each other than to generalist scavenging species.

Secondly, changes were ascribed to either turnover or nestedness. Turnover occurs when species (or functional types)
are replaced by new ones at different parts of the gradient. Nestedness describes a pattern of species loss whereby some sites are
simply “nested subsets” of those with more species.

“We found that different species occupied different elevations in a turnover pattern,” said Tom
Bishop, lead author of the paper published in Journal of Biogeography. He adds, “As you climb the mountain, however,
these new species tend to occupy a smaller and smaller subset of the functional types available. This is a pattern of functional
nestedness. These results allow us a greater understanding into the factors that may be shaping ant ecology and biology in harsh,
mountain environments.”